Combustion-powered, fastener-driving tools of the type noted above are exemplified in but not limited to Nikolich U.S. Pat. No. 5,197,646, Nikolich U.S. Pat. No. Re. 32,452, Nikolich U.S. Pat. Nos. 4,522,162, 4,483,474, and 4,403,722, and Wagdy U.S. Pat. No. 4,483,473. Such combustion-powered tools are available commercially from ITW Paslode (a unit of Illinois Tool Works Inc.) of Lincolnshire, Ill., under its IMPULSE trademark.
Generally, a combustion-powered, fastener-driving tool of the type noted above comprises a combustion chamber, into which a combustible fuel is injected, and in which the fuel is mixed with air and ignited. Moreover, a driving piston mounting a driving member is arranged to be axially driven within a driving piston cylinder, so as to drive the driving member from a retracted position into an extended position, upon combustion of the combustible fuel in the combustion chamber.
In pneumatically powered, fastener-driving tools, particularly such nail-driving tools, it is known to employ pressurized air-actuated, fastener-feeding mechanisms. Generally, such a pressurized air-actuated, fastener-feeding mechanism comprises a feeding mechanism cylinder and a feeding piston. Moreover, the feeding piston is movable within the feeding mechanism cylinder between a withdrawn position and an advanced position and is biased toward the advanced position, and a feeding claw mounted to the feeding piston is movable for engaging at least one fastener from a collated strip of fasteners when the feeding piston and the feeding claw are in the withdrawn position and for feeding a leading fastener from such a coil into the nosepiece when the feeding piston is moved from the withdrawn position into the advanced position. Combusted gases is diverted from the driving piston cylinder, ahead of the driving piston, into the feeding mechanism cylinder so as to move the feeding piston from the advanced position toward the retracted position when the driving piston is driven.
In pneumatically powered, fastener-driving tools provided with such gas-actuated, fastener-feeding mechanisms and available commercially from ITW Paslode, supra, under its PASLODE trademark, it is known for gases to be taken in substantially at an endmost location in the driving piston cylinder, beyond the position reached by the driving position when the driving member reaches the extended position.
In Japanese Laid-Open Utility Model Application No. 5-72380, which was laid open on Oct. 5, 1993, it is suggested to employ a gas-actuated, fastener-feeding mechanism in a combustion-powered, nail-driving tool of the type noted above. In a first embodiment illustrated in FIG. 1 of that Application, combusted gases taken in from a combustion chamber is diverted to actuate the fastener-feeding mechanism, so as to allow very little if any delay between driving of the driving piston and movement of the feeding piston from the advanced position into the withdrawn position. In a second embodiment illustrated in FIG. 10 of that Application, combusted air to be so diverted is taken in approximately where the driving piston ends its driving stroke, so as to apply a very short pulse of high pressure to the feeding piston.
However, it has been found that neither location illustrated in Japanese Laid-Open Utility Model Application No. 5-72380 is an optimum location for taking in combusted gases to actuate a gas-actuated, fastener-feeding mechanism in a rapidly acting, fastener-driving tool, particularly in a combustion-powered, fastener-driving tool of the type noted above. Moreover, the endmost location known in pneumatically powered, fastener-driving tools discussed above is not an optimum location therefor.